Equipment for the combustion of oils of differing viscosity by means of atomization in light-oil burners



F. DRESING 3,067,809 EQUIPMENT FOR THE COMBUSTION OF OILS OF DIFFERING Dec. 11, 1962 VISCOSITY BY MEANS OF ATOMIZATION IN LIGHT-OIL BURNERS 2 Sheets-Sheet 1 Filed Oct. 7, 1959 1962 F. DRESiNG 3,067,809

EQUIPMENT FOR THE COMBUSTION 0F OILS 0F DIFFERING VISCOSITY BY MEANS OF ATOMIZATION IN LIGHT-OIL BURNERS 2 Sheets-Sheet 2 Filed Oct. 7. 1959 mvmozz fiflrasiny ATTORNEYS ire hoe EQUIPMENT FOR THE CGMBUSTKQN F GILS 0F DIFFERKNG VISCOSITY BY MEANS OF ATOMIZATiGN IN LIGHT-01L EURNERS Fritz Dresing, House Margaretta, Bad Essen, Osnabrucir, Germany Filed Oct. '7, 1959, Ser. No. 844,990 Claims priority, application Germany Get. it), 1958 6 Claims. (Cl. 158-365) The invention relates to an appliance for the combustion of oils of differing viscosity by means of atomization in light-oil burners. Appliances of this kind are known which, using a return-flow pipe, allow the oil, pro-heated, to circulate in the combustion pipe, and in which the entry of the oil into the spray diffuser is automatically controlled, this latter operation being effected by means of time-control gear. Such appliances respond slowly since they are dependent on the time at which the timecontrol gear has been set, which latter has to be set to the maximum time which the highest viscosity oil being used takes to warm up. Nor are they completely safe operationally since they allow the oil to flow to the atomizing jet even when, for some reason or other the oil has not attained, during the time it has been warmed up, the degree of fluidity necessary for the atomization process.

The purpose of the present invention is to provide an improved appliance which, first and foremost, ensures that the flow of the oil to the nozzle is controlled according to the viscosity of the oil and independent of a predetermined time setting. The purpose of the invention is further to design the appliance in such a way that the flame is ignited gently and not suddenly, i.e. explosion-like, but gently. It is intended also that important operational considerations relating to an automatic firing, such as a prior firing of the boiler, and emptying the nozzle tip by suction when the flame is extinguished, shall also be effected. Additionally, the aim is to employ few operationally safe parts in the construction of the appliance which will be distinctive by its maximum operational safety.

To this end the invention consists of the fact that, in the return-flow pipe there is provided a shut-off memher which is so controlled by a component located in the oil stream and set into vibration by the oil stream, that, when oscillating gently, itbrings about a temporary throttling down in the rhythm of the oscillations, and when vibrating with a greater amplitude it sets up a closure of the oil circulation caused by the oil pressure, and that, in front of the atomizing jet there is provided a non-return valve which is closed when there is no oil pressure, it being preferable for the oscillating component and the non-return valve with its spring to be so matched to each other that whenever there is a slight viscosity in the oil, and more particularly so with the customary light-oil, the valve casing, by virtue of the temporary throttling down of the oil circulation, comes into resonance with the oscillating component and, as a result, opens and closes the non-return valve, in opposition to the spring, in the rhythm of the oscillations, and releases the supply of the oil to the atomizing nozzle, until such time as, the oil circulation being permanently blocked, the non-return valve opens up fully. It is preferable for the oscillating component to be made of heat-sensitive material, bimetal for example. It is a useful measure for the oscillating component to be capable of adjustment by means of a set screw which is operated externally, complete with an indicator corresponding to the viscosity of the oil. It is further possible to provide, in addition to the oscillating component, further heatsensitive components which, upon becoming cold, lift from its seating the shut-off member operated by the oscillating component. What is more, the oscillating component may be attached to a block in the return-flow pipe, this block being made of two sections with oblique contact surfaces which are mutually displaceable by means of a set screw. As a matter of preference the cylinder shaft of the non-return valve can be equipped, on its circumferential surface, with axially directed recesses which have their outlets in an annular space adjoining which there is a disc piston which is seated on the valve shaft. The disc piston seals off the oils flow cross section to the valve disc. piston to be bevelled on its side turned towards the shaft.

A further feature of the invention consists in the fact that, in the course of the practically pressure-free pumpence to the accompanying drawings which represent one" example of execution of the subject of the invention. In these drawings:

FIG. 1 shows a valve, designed and fitted, according to the invention, in the return-flow pipe, open, and repre-'.

sented in vertical section,

FIG. 2 shows the valve in accordance with FIG. 1, in a closed state,

FIG. 3 shows a non-return valve in accordance with the invention, in vertical section,

FIG. 4 shows the valve in accordance with FIG. 3 in another working position,

FIG. 5 is a diagrammatic view showing the invention installed in an oil-fired heating plant,

FIG. 6 is a fragmental vertical sectional view of the block assembly to which the oscillating component is attached,

FIG. 7 is a view looking in the direction of the arrow in FIG. 6, and,

FIG. 8 is a view taken along line 8-8 of FIG. 3, the view being on a larger scale.

Referring to FIG. 5, there is illustrated the general system of an oil-fired heating plant in which the present invention is installed. The plant includes a preheater 22 with a heating element 23, a temperature limit control 24 for limiting the highest temperature, and an adjustable thermostat 25 which, for example, can be adjusted up to C. for light oil and up to C. for heavy oil.

The oil is conducted from a supply container, not shown, via a conduit 26 to the preheater 22, and conduit 27 serves for venting the preheater. The preheater is connected via a conduit 28 to an oil pump 29 which, together with a blower 30, is driven by an electric motor 31. The oil conveyed by means of pump 29 is conducted through a conduit 32 to a valve which is designated generally with 11 to 16, in FIGS. 3 and 4, and which will later be more fully described. A return conduit 1 leads to valve designated generally 3 to 9', in FIGS. 1 and 2, and which will hereinafter be described in detail. A pipe 2 connects this latter valve to the preheater.

The valve in FIGURES 1 and 2 is located in a housing H between return-flow pipe 1 and pipe 2. The valve is defined by a fiat bar 3, preferably of resilient metal. On its free end, the bar carries a shaped member 4 preferably in the shape of a lid, cone or ball, such as is suitable for Patented Dec. 11, 19 2 It is also possible for the disc thickly viscous-oil is ensured. The mounting block 5, 7 itself consists of two parts, the oblique side surfaces of which make an adjoining fit but which can be mutually displaced, and held secure in the particuiar position desired by means of a screw 8. As shown in FIG. 7, the sides of the blocks are planar, thereby providing channels 6', 7' through which the oil may flow. If the screw 3 is tightened, the block part 6 is moved along the oblique surface in an upward direction. Its upper limit abuts the housing wall and hence both block parts jam on the inner wall of the housing H so that a longitudinal movement of both block parts is no longer possible. If the screw 8 is loosened, the jamming is eliminated and both block parts can be moved together longitudinally within the housing. Thus, in such a simple manner it is possible for the flat bar to be set accurately. As shown in FIG. 1, the housing H is equipped with a drilled hole 19 complete with internal thread, into which a set screw 20 with a pointer 21 is screwed and which makes it possible to alter the initial tension of the flat bar 3 and thus enable the valve to be adjusted easily from the outside corresponding to the viscosity of the oil.

When the oil is being pumped through the circulatory pipe arrangement the bar 3 is set in vibration by the oil as it flows past the bar. The attenuation action of the oil influences the frequency of oscillations, the attenuation being smaller the more the viscosity of the oil flowing past is reduced by the heating action. The reduction in the attenuation action results in the bar 3 oscillating at a wider amplitude accordingly and thus approaches more closely, with its member 4, to the aperture 5. Because of the oscillations becoming stronger, an alternating resistance is set up to the passage of the oil and thus the oscillations are reproduced in the entire piping system through which the oil flows and make their presence felt on a nonreturn valve 11, 12, 16 (FIGS. 3, 4) located in a nozzle tip 17. The non-return valve components, in accordance with the invention, can be so set that, upon a specific frequency of oscillations having been reached, such valve becomes resonant. The moment the non-return valve is set in motion in this way it only allows, initially, small quantitles of oil to pass through into the nozzle tip 17 where the oil is atomized and ignited on the igniter which is already in operation. In this way, the problem is solved of not letting the flame start up in a sort of detonation, but gently. By the wider oscillation of the bar 3 a situation soon is reached in which the member, 4, during one oscillation, comes so close to the aperture that it is struck by the full pressure of the oil and pressed tight on the aperture 5, thereby sealing the aperture.

Thus, the return-flow pipe is interrupted and the pressure of the oil pump 29 from now on is exerted fully on the non-return valve 11, 12, 16, in front of the nozzle tip 17 which opens up correspondingly and makes possible a full development of the flame.

In the design of the non-return valve (FIGS. 1, 2) as has been described, a certain specific distance as between the aperture 5 and the member 4- must not be exceeded as otherwise the oscillations necessary for the functioning of the valve would not result. But it is important, particularly when firing heavy oil, that at the commencement of the circulatory pumping operation, there shall be an unhindered fiow of the viscous oil. Consideration can be given to this requirement also by the further development of the invention as described hereunder.

In accordance therewith, the flat bar 3 is made of bimetal which, as is well known, has the property of bending under the influence of heat. The bimetal bar is now fitted, according to the invention, in such a way that, in its rest position, it holds the member 4 at a suflicient distance away from the aperture 5 that it does not impede the free passage of the oil. It is not until the oil has been heated and thus rendered less viscous that the bimetal bar 3 bends under the influence of the heat in such a way that it brings the member 4 as close to the aperture 5 as is neces' sary to enable the oscillations already described to result.

Now however, it is necessary to ensure that the operational processes as outlined above shall be repeated each time the equipment has been switched off temporarily as is particularly the case when the prescribed heating temperature has been reached, for the oil cools off again a a result of the equipments being out of service temporarily. What is more, consideration has to be given to the possibility that the oil pumps pressure regulating valve (not depicted) might, by its shutter, and especially when drawing oil out of a low-lying tank, bring about a vacuum in that portion of the oil-pipe located between the pump and the non-return valve. This would draw the member 4 tight on the aperture 5 and make it difficult, if not prevent altogether, the valve from opening again so as to make possible a renewed circulatory pumping operation.

For this purpose, there is fitted according to FIGURES 1 and 2, under or over the bar 3 one or more heat-sensitive components 9 in such a way that they are a sutficient distance away from the bar 3 so as not to hamper the latters oscillations. The components 9 are made, as a matter of preference, of bimetal strips which, while the warmed oil is circulating, bend in such a way that the valve 3, 4, 5, is able to close unhindered in the manner described. If the oil should become cold as a result of the equipments having been put out of service, the components 9 will return to their rest position and, depending on the way in which they are fitted, either lift or pull the bar 3 together with member 4 away from the aperture 5. In this way any vacuum which might otherwise have been set up is eliminated and the equipment is again ready for service.

In order to ensure that the nozzle tip 17 shall be sucked free of oil residue when the equipment is switched off, the valve is designed in the special manner as shown in FIG. 3. A valve shaft 10 which moves to and fro in guide 11 is provided with, immediately to the rear of sealing cone or head 12, a piston-like shape 13. The remainder of the shaft is primarily determined as regards its shape by a circumferential recess 14 and then by iongitudinal recesses 15, as may be seen in FIGS. 3 and 8. A spring 16 ensures that, when the equipment is idle, the valve is closed, in that it presses the valve cone 12 against the flow aperture. In this state, the piston 13 also shuts oh? the feed cylinder completely which acts simultaneously as a guideway for the shaft. Now when, in the manner already described, the pressure of the oil pump 29 begins to act against the non-return valve, it drives the piston 13 out of the guideway so that the oil is then able to flow, through the recesses 13 in the valve shaft, and into the nozzle tip 17. This operation in turn brings about a fall-off in pressure and thus the piston 13 slides back under the influence of the spring 16 and re-enters the guideway 11. The oil pressure which immediately builds up again, again drives it out and this procedure is repeated in rapid succession. The constant to and fro movement of the piston 13 is at the same time beneficial to the atomization of the oil. Now, if the equipment is switched off, the pressure of the oil pump will suddenly fall off, and the piston 13 will speed hack into the guideway for the last time thereby setting up a vacuum between the valve, which is now closed off tight, and the nozzle tip. In this way the oil residue will be aspirated from the tip.

When designing the shape of the valve piston 13 how ever, one physical peculiarity has to be given consideration. If the piston were to be given a purely cylindrical shape, there would be set up, by the rapid to and fro movement, a high-frequency air oscillation which would make itself conspicuous by a penetrating and unpleasant Whistling noise. This undesirable secondary effect is, preferably, prevented in that the piston is bevelled on the side facing the shaft as shown at 18. In this way the whistling noise disappears completely.

For the sake of giving a complete picture mention should still be made of the fact that an additional device is necessary for bringing the operational processes outlined into coordination with the customary control equipment of a fully automatic oil-firing installation. This, as a general rule, makes provision for the fact that, when the installation is put into operation, a supervisory mechanism starts to operate, preferably by light control, which leaves the installation switched on only on condition that an adequate flame is available. Since, in accordance with the invention, a circulatory pumping operation takes place first of all and the flame does not form until later, precautions have to be taken to ensure that the supervisory equipment referred to, which in this state of operation does not need to exercise any supervisory function, does not come into operation before the requisite conditions for the formation of the flame have been established. This as achieved, in the most simple manner, by locating in the conduit 32 between the pump 29 and the valve unit 11-16 a pressure switch of known constructional type. The pressure switch has to operate in such a way that, where there is an absence of pressure, it puts the supervisory equipment referred to out of operation. Indeed, during the circulatory pumping operation there is normally no appreciable pressure in the oil line. This pressure is only set up when the stage is reached for the atomization to commence and the flame to be formed. Then however the supervisory equipment is allowed to come into operation and at the same time the supervision of the flame is ensured.

If, on the other hand, a situation should happen to arise in which foreign bodies are present in the pumped oil which render the friction-free and hence pressure-free circulation diflicult, or hinder the same, this would result in the pressure switch being actuated as a result of the rise in pressure. The effect of this would be that the supervisory gear would be set into operation. Since however, in this instance, no flame, or only an inadequate flame would be able to form, the burner would be switched off and a warning signal emitted.

What I claim is:

1. Equipment for the combustion of oils of varying viscosity of the type including an atomizer nozzle, means for circulating the oil, conduit means leading from the circulating means to the atomizer nozzle, a return-flow conduit means communicating with the atomizer nozzle and the circulating means, a preheater means in the return-flow conduit means, shut-oil member in the returnflow conduit means, a component within said return-flow conduit means operably associated with said shut-01f member adapted to be set into vibration by the oil stream so that when such component vibrates with small oscillations it effects in the rhythm of the oscillations, a temporary throttling-down of the oil return circulation and when the oscillations reach a large amplitude, the shutoiE member closes the return-flow conduit means and is maintained in such position by the oil pressure produced by the circulating means, a non-return valve having a valve body and a spring operably coupled to the valve body located in advance of the atomizer nozzle and in communication with said conduit means, said non-return valve being closed when there is no oil pressure, and said component and non-return valve being so attuned to each other that whenever the oil is of slight viscosity, the valve body due to the temporary throttling-down of oil circulation comes into resonance with said component thus opening and closing the valve body in opposition to said spring in the rhythm of the oscillations thereby providing varying access for the oil to the atomizer nozzle until such time as the oil return circulation is completely arrested due to the shut-oft" member being held closed by the oil pressure so that the non-return valve remains steadily open.

2. Equipment as claimed in claim 1, wherein the vibrating component is made of a material capable of being warped by temperature changes.

3. Equipment as claimed in claim 1 including a set screw operably connected to the vibrating component for adjusting said component from the outside, and an indicator on the set screw which corresponds to the viscosity of the oil.

4. Equipment as claimed in claim 1, including in addition to the vibrating component, further means capable of being warped by temperature changes which, upon becoming cold, lift the shut-off member operated by the vibrating component oil its seat.

5. Equipment as claimed in claim 1, in which said valve body is provided with a cylindrical shaft, said shaft being provided on its circumferential surface with axially directed recesses which have their outlet in a ring-shaped chamber, .a disc piston on the shaft adjoining said recesses and having a bevelled surface on the side facing the recesses and which seals off the fiow passage of oil to the valve body.

6. Equipment as claimed in claim 1, wherein in the course of a practically pressure-free circulatory pumping operation, a switch, which is operated by the oil pressure, serves to ensure that the entire control gear only comes into operation when the atomization of the oil begins.

References Cited in the file of this patent UNITED STATES PATENTS 2,173,814 Bischof Sept. 19, 1939 2,199,454 Andler et a1. May 7, 1940 2,665,167 High Jan. 5, 1954 

